Bacterial Force on Nanopillars: Interaction at Single Cell

Despite extensive studies there are contradictory findings regarding effects of nano-topography on bacterial adherence and viability. Here, we report that bacteria have ability to locate nearest pillars, enabling itself to expand and attach, and pulling these pillars towards itself. Two types of nanopillars, namely, Straight pillars (SP) and Conical pillars (CP) were used to investigate the behavior of bacterial cell on surface nano topographies. We calculated that the force applied by the bacteria on these pillars is in the order of few hundred nano-newtons, and most importantly, the magnitude of the applied force depends on the pillar dimensions. Straight pillars are bent significantly compared to sharp-tipped conical pillars, suggesting higher overall mechanical stress in/throughout the bacterial membrane on straight pillars, leading to membrane rupture and ultimately cell death. In the case of bacterial membrane on conical pillars, severe localized stress generated in the membrane, near the regions where pillars contacted the membrane due to small cross-section of conical pillars, pierces the membrane (no bending of pillars) which causes cell death.